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        <div style="margin: 0px 10px 8px 10px"  class="pagetitle">S2-004</div>

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            <div id="ConfluenceContent"><h2 id="S2-004-Summary">Summary</h2>
<p>
</p><p>Directory traversal vulnerability while serving static content</p>
<div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Who should read this </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> All Struts 2 developers </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Impact of vulnerability </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Read access to server filesystem resources (under certain application server environments) </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Maximum security rating </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Important </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Recommendation </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Developers should upgrade to <a shape="rect" class="external-link" href="http://people.apache.org/builds/struts/2.0.12/">Struts 2.0.12</a> </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Affected Software </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Struts 2.0.0 - Struts 2.0.11.2 </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Original JIRA Ticket </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> <a shape="rect" class="external-link" href="https://issues.apache.org/struts/browse/WW-2779">WW-2779</a> </p></td></tr><tr><th colspan="1" rowspan="1" class="confluenceTh"><p> Reporter </p></th><td colspan="1" rowspan="1" class="confluenceTd"><p> Csaba Barta and L&#225;szl&#243; T&#243;th, PricewaterhouseCoopers </p></td></tr></tbody></table></div>


<h2 id="S2-004-Problem">Problem</h2>

<p>The Struts2 dispatcher logic by design allows to serve certain static resources found in the classpath of the web application for request URIs having a context relative path starting with "/struts/".</p>

<p>FilterDispatcher (in 2.0) and DefaultStaticContentLoader (in 2.1) have a security vulnerability that allows an attacker to traverse the directory structure and download files outside the "static" content folder, using double-encoded urls and relative paths, like:</p>

<p><a shape="rect" class="external-link" href="http://localhost:8080/struts2-blank-2.0.11.1/struts" rel="nofollow">http://localhost:8080/struts2-blank-2.0.11.1/struts</a>..</p>

<p><a shape="rect" class="external-link" href="http://localhost:8080/struts2-blank-2.0.11.1/struts/..%252f" rel="nofollow">http://localhost:8080/struts2-blank-2.0.11.1/struts/..%252f</a></p>

<p><a shape="rect" class="external-link" href="http://exampletomcat.com:8080/struts2-blank-2.0.11.1/struts/..%252f..%252f..%252fWEB-INF/classess/example/Login.class/" rel="nofollow">http://exampletomcat.com:8080/struts2-blank-2.0.11.1/struts/..%252f..%252f..%252fWEB-INF/classess/example/Login.class/</a></p>

<p>Although not all container are vulnerable to this, the Struts2 dispatcher logic has to prevent access to static content outside the static resource folders.</p>

<h2 id="S2-004-Solution">Solution</h2>

<p>As of Struts 2.0.12, the dispatcher logic was improved to correctly decode and normalize the request path before checking if static content serving applies for a given request.</p>

<p>You can obtain <a shape="rect" class="external-link" href="http://people.apache.org/builds/struts/2.0.12/">Struts 2.0.12</a> as a drop in replacement for Struts 2.0.11.2 to get the fixed Struts 2 core library.</p></div>
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